Macro typed_index_collection::impl_id

macro_rules! impl_id {
    ($ty:ty, $gen:ty, $id: ident) => { ... };
    ($ty:ty) => { ... };
}

Implements the Id trait for an object. For example, if an object Animal has a field 'species_id' which is a pointer toward another Object of type Species, you can implements Id with the following example. You can also implement Id for Animal itself (the identifier of an Animal is its own field that must be named id).

struct Species {
  id: String,
  name: String,
}
struct Animal {
  id: String,
  name: String,
  species_id: String,
}
impl_id!(Animal, Species, species_id);
impl_id!(Animal);